The effect of dioptric blur on reading performance

Area of Science:

• Ophthalmology
• Vision Science
• Human Factors

Background:

• The effects of optical blur on reading performance are not well understood.
• Quantifying blur's impact is crucial for understanding visual function limitations.

Purpose of the Study:

• To systematically quantify the impact of dioptric blur on reading performance in young adults with normal vision.
• To determine how different levels of blur affect reading speed, acuity, and required print size.

Main Methods:

• 19 normally sighted adults participated, with induced dioptric blur (0 to 3D) using trial lenses.
• Monocular reading performance was measured using the MNREAD Acuity Chart at various print sizes.
• Visual acuity was assessed using Landolt C stimuli.

Main Results:

• Maximum reading speed was largely unaffected by blur up to 2D, but decreased by 23% with 3D of blur.
• Threshold print size increased significantly with blur, from 0.01 to 0.88 logMAR (0 to 3D).
• Reading acuity and visual acuity worsened considerably with increasing blur, correlating with threshold print size changes.

Conclusions:

• Visual acuity is a reliable predictor of reading acuity and the print size needed for maximum reading speed.
• Reading performance, like visual acuity, is degraded by optical blur.
• Higher levels of blur necessitate larger print sizes to achieve optimal reading speed.